HD 233731
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 10h 22m 43.59244s[1]
Declination +50° 07′ 42.0635″[1]
Apparent magnitude (V) 9.732[2]
Characteristics
Spectral type G5V[3]
B−V color index 0.86[3]
Astrometry
Radial velocity (Rv)12.63±0.26[1] km/s
Proper motion (μ) RA: −26.182[1] mas/yr
Dec.: 83.727[1] mas/yr
Parallax (π)12.2014 ± 0.0371 mas[1]
Distance267.3 ± 0.8 ly
(82.0 ± 0.2 pc)
Absolute magnitude (MV)5.22±0.14[2]
Details[3]
Mass0.936+0.028
−0.033 M☉
Radius1.062+0.046
−0.013 R☉
Luminosity0.77±0.09[2] L☉
Surface gravity (log g)4.357+0.039
−0.005 cgs
Temperature5,314±50 K
Metallicity [Fe/H]0.30±0.09 dex
Rotation28.7±0.4 d
Rotational velocity (v sin i)1.65±0.26 km/s
Age9.0+1.4
−2.2 Gyr[3]
12.4±2.6[2] Gyr
Other designations
HAT-P-22, Gaia DR2 846946629987527168, HD 233731, TYC 3441-925-1, GSC 03441-00925, 2MASS J10224361+5007420[4]
Database references
SIMBADdata

HD 233731, or HAT-P-22, is a suspected multiple star system in the northern circumpolar constellation of Ursa Major. It is invisible to the naked eye, having an apparent visual magnitude of 9.732.[2] This system is located at a distance of 267 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +13 km/s.[1]

The stellar classification of the primary is G5V,[3] matching an ordinary G-type main-sequence star. The star has a low level of stellar activity with an estimated age of 9 to 12 billion years old. Its metallicity is twice that of the Sun, unusual for its advanced age.[3] HD 233731 has a similar mass and radius as the Sun, and is spinning with a rotation period of 28.7 days.[3] It is radiating 77%[2] of the luminosity of the Sun from its photosphere at an effective temperature of 5314 K.[3]

A faint stellar companion (2MASS J10224397+5007504) with a red hue is located at an angular separation of 9 arcseconds from the primary.[2] In 2015, a spectroscopic stellar companion was reported with a semimajor axis of less than 33 AU. This star has an effective temperature of 4,000+250
−400 K with a mass of 0.63+0.07
−0.17 M☉.[5]

Planetary system

In 2010 a transiting hot Jupiter like planet was detected, designated HAT-P-22b.[2] It has an equilibrium temperature of 1,463±19 K, and planetary atmosphere is cloudy.[6] The measurement of Rossiter-McLaughlin effect in 2018 has allowed to detect what the planetary orbit is well aligned with the equatorial plane of the star, with a misalignment angle equal to 25°±18°.[3]

In 2017, analysis of additional HARPS data showed a long-term trend that suggested the presence of an additional orbiting companion, HAT-P-22c.[7]

Size comparison of HAT-P-22 b and Jupiter
The HAT-P-22 planetary system[2][3][7]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 2.192+0.073
−0.013 MJ		 0.04171+0.00042
−0.00050		 3.21223328 0.016±0.009 86.46±0.41° 1.060±0.048 RJ
c (unconfirmed) ≥3.0 MJ — ≥20.8 years — — —

References

  1. 1 2 3 4 5 6 7 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 1 2 3 4 5 6 7 8 9 Bakos, G. Á.; et al. (2010), "HAT-P-20b – HAT-P-23b: Four Massive Transiting Extrasolar Planets", The Astrophysical Journal, 742 (2): 116, arXiv:1008.3388, Bibcode:2011ApJ...742..116B, doi:10.1088/0004-637X/742/2/116, S2CID 119182075.
  3. 1 2 3 4 5 6 7 8 9 10 Mancini, L.; et al. (2018), "The GAPS programme with HARPS-N at TNG XVI. Measurement of the Rossiter-McLaughlin effect of transiting planetary systems HAT-P-3, HAT-P-12, HAT-P-22, WASP-39, and WASP-60", Astronomy & Astrophysics, A41: 613, arXiv:1802.03859, Bibcode:2018A&A...613A..41M, doi:10.1051/0004-6361/201732234, S2CID 73565379.
  4. ↑ "HD 233731". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2015-12-10.{{cite web}}: CS1 maint: postscript (link)
  5. ↑ Piskorz, Danielle; et al. (2015), "Friends of Hot Jupiters. III. An Infrared Spectroscopic Search for Low-Mass Stellar Companions", The Astrophysical Journal, 814 (2): 148, arXiv:1510.08062, Bibcode:2015ApJ...814..148P, doi:10.1088/0004-637X/814/2/148, S2CID 11525988.
  6. ↑ Turner, Jake D.; et al. (2016), "Ground-based near-UV observations of 15 transiting exoplanets: Constraints on their atmospheres and no evidence for asymmetrical transits", Monthly Notices of the Royal Astronomical Society, 459 (1): 789–819, arXiv:1603.02587, Bibcode:2016MNRAS.459..789T, doi:10.1093/mnras/stw574, S2CID 8769245.
  7. 1 2 Bonomo, A. S.; et al. (2017), "The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets", Astronomy and Astrophysics, 602, A107, arXiv:1704.00373, Bibcode:2017A&A...602A.107B, doi:10.1051/0004-6361/201629882.
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